The present invention relates to an aircraft taxiing, in particular a civil or military, passenger or freight transport airplane or even a drone. It more particularly relates to generating a yaw moment (according to the vertical axis of the aircraft) allowing to laterally control the taxiing aircraft.
Within the framework of the present invention, taxiing means any possible type of running for an aircraft, such as either running on a landing runway during landing and take off phases, or running on traffic lanes or on maneuvering areas, in particular.
Today, the pilot controls the lateral movements of the aircraft on the ground using manual command units (for example, a hand wheel allowing to orient the wheel of the front landing gear, a joystick for controlling the engine thrust, brake pedals, a directional crossbar), along a trajectory on the ground. Such command units allow to control actuators of the aircraft being able to influence the lateral movements of the aircraft, essentially through the orientation of the front wheel (and optionally the orientation of the rear gears) and the drift rudder, and more rarely, via an asymmetrical use of the engines and brakes.
Within the context of the present invention, a front wheel means a mechanical assembly being provided with at least one wheel, being located at the front of the aircraft, preferably being part of a front landing gear of the aircraft, and being orientable so as to be able to laterally shift the aircraft when the latter is taxiing.
Currently, in the event of a breakdown of the orientation system of the front wheel (for example, in the event of a loss from the hydraulic system supplying the actuator responsible for the orientation, in the event of a breakdown of the actuator itself, or even in the event of a loss of data transmission between the calculator controlling the actuator and the latter), the aircraft could no longer be laterally controlled through the usual command units (hand wheel, directional crossbar), and this, more especially, at a low speed, when the rudder has no significant effect any more on the yaw moment of the aircraft.
Sometimes, such types of breakdown occur in flight or after landing, which could make the landing phase risky. In the event of a loss of control of the front wheel, landing could no longer be performed by an automatic control system, and the pilot can only use the directional rudder, as well as, optionally, the brakes on an asymmetrical way thanks to the brake pedals, a maneuver the pilot is however not familiar with. Such a situation can be found to be difficult, or even dangerous, and lead to a runway excursion, at a more or less high speed if the pilot does not succeed to properly control the aircraft (for example because of a side wind, a breakdown of an engine, . . . ), which could lead to human and/or material losses or damage.
Once the aircraft stopped at the end of the runway, it is still possible to laterally control it, using the brakes and/or the engines on an asymmetrical way, and this, in order to quickly clear the runway and make it available for the aircrafts that are to land or to take off. However, the operational directive of airlines generally consists in compelling the pilot, taking in consideration the risky and potentially dangerous control resulting from the asymmetrical manual use of the brakes and/or the engines, to call on the ground traffic control so as to dispatch a towing tractor for towing the aircraft from the end of the runway to a cleared area of the airport (relation way, landing gate, . . . ). Indeed, the manual lateral control of an aircraft exclusively making use of the asymmetrical use of the brakes and engines could be found to be particularly difficult for a pilot not being familiar with such a maneuvering type, all the more as control could be found already difficult for large size aircrafts (for example of the AIRBUS A340-600 or A380 type) when the front wheel correctly operates (need to use an outside camera in sharp turns).
During the waiting time for the towing tractor and the towing time, the aircraft thus obstructs the runway and consequently disturbs the traffic on the ground (aircrafts to take off must wait, modification of the trajectory of the aircrafts on the ground if their progression is impacted by the aircraft being towed), as well as the air traffic (possible diversion to other airports for aircrafts that were in the approach phase, take-off delay for the aircrafts waiting for the runway to be released). Such a situation results in potentially significant delays, both for the broken down aircraft as well as for the aircrafts impacted by the air traffic and the traffic on the ground being disturbed. Such delays result in high costs for the airlines (in particular, financially and materially compensation for passengers, more specifically should the aircrafts be diverted).
Furthermore, the aircraft is grounded while the breakdown is being repaired. Such grounding time could be particularly long should spare parts not be available at the airport, or should repair not be made at the airport, in particular if the airport is isolated (or if it is located in a remote country). The grounding costs for an aircraft are thus particularly high, more specifically it the spare equipment is to be supplied from a remote location or if an additional aircraft is to be chartered for ensuring the air link and/or for repatriating the passengers.